The present invention relates to a water-based endothermic fire protective material comprising a heat curable thermosetting resin, inorganic fibers, endothermic inorganic filler and thermoplastic resin which is particularly useful for fire stopping purposes.
In commercial buildings, electrical cables, electric cable trays and telephone cable trays pass through penetrations in walls, floors and ceilings. The penetrations for these members are necessarily somewhat larger than the members themselves. In the event of a fire, it is possible for flames, heat and smoke to pass through these penetrations thereby spreading the fire and smoke.
The possibility of fires in areas with high concentrations of instrument and communication wires as well as power transmission cables is of great concern in automated industrial plants. Communications and power cables are manufactured with combustible electrical insulation sheaths which can provide a fuel pathway to enable a fire to spread. Although floors, walls and ceilings serve as a discrete barrier to contain a fire in a room, such fires need to be arrested by properly designed fire protective materials placed not only around the cable runs but also for use in filling the gaps and interfaces in the penetrations. In this manner the fire can be contained to permit an orderly shutdown to isolate the system and extinguish the fire with minimal spread and damage.
Cable and communications systems manufacturers are acutely aware of the problem and have directed considerable research efforts towards developing systems characterized by low flame spread and particularly lower fuel load. There are a number of methods described in the patent prior art relating to the sealing of the openings around pipes and cable members. Silicone foams have been used but have the difficulty of position retention until the foam is set. Other means include stuffing the penetration with inorganic fibers. However, these fiber batts do not always stay in place and can be easily dislodged.
Compositions employing char-forming, endothermic, intumescent, and/or sublimation reactions from the heat from fires are disclosed in various forms. For example, U.S. Pat. No. 3,849,178 discloses a subliming and endothermic phase change coinciding with an intumescent char-former when exposed to fires. The active components and binders in this composition must be thermoplastic and soften or melt to carry out the sublimation endothermic outgasing process in order to be effective. U.S. Pat. No. 4,189,619 discloses compositions containing fusing ceramic, hydrous metal oxides, intumescent solids, and binder solids which are thermoplastic resins. U.S. Pat. No. 4,363,199 also uses hydrous metal oxides along with a substantial amount of an inorganic binder, colloidal silica, acting as a refractory adhesive when exposed to high temperatures In U.S. Pat. No. 4,600,634, highly filled endothermic fibrous sheet materials utilizing minimal amounts of resinous binders that are also thermoplastic are disclosed. Utilizing formulations in which the fusible ceramic solids are activated during a fire and fuse at 700.degree.-1500.degree. F. temperature range (U.S. Pat. No. 4,189,619) or where the colloidal silica is fused at high temperatures to increase its strength during a fire (U.S. Pat. No. 4,363,199) limits the amount of active ingredients (e.g., subliming, endothermic, intumescent) that can be used because the relatively large temperatures. amounts of inorganic thermally fusible material comprises a significant portion of the compositions.